Lidar pixel with active polarization control

ABSTRACT

A light detection and ranging (LIDAR) pixel includes a polarization controller, a grating coupler, and an optical mixer. The polarization controller includes a phase shifter that sets a phase of light in a first arm of the polarization controller and a second arm of the polarization controller.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. provisional Application No.63/038,452 filed Jun. 12, 2020, which is hereby incorporated byreference.

TECHNICAL FIELD

This disclosure relates generally to imaging and in particular to aLIDAR (Light Detection and Ranging).

BACKGROUND INFORMATION

Frequency Modulated Continuous Wave (FMCW) LIDAR directly measures rangeand velocity of an object by directing a frequency modulated, collimatedlight beam at a target. Both range and velocity information of thetarget can be derived from FMCW LIDAR signals. Designs and techniques toincrease the accuracy of LIDAR signals are desirable.

The automobile industry is currently developing autonomous features forcontrolling vehicles under certain circumstances. According to SAEInternational standard J3016, there are 6 levels of autonomy rangingfrom Level 0 (no autonomy) up to Level 5 (vehicle capable of operationwithout operator input in all conditions). A vehicle with autonomousfeatures utilizes sensors to sense the environment that the vehiclenavigates through. Acquiring and processing data from the sensors allowsthe vehicle to navigate through its environment. Autonomous vehicles mayinclude one or more FMCW LIDAR devices for sensing its environment.

BRIEF SUMMARY OF THE INVENTION

Implementations of the disclosure include a light detection and ranging(LIDAR) system including a laser, a splitter, a polarization controller,and a dual-polarization grating coupler. The laser is configured togenerate light. The splitter is configured to split the light into aplurality of lights. The polarization controller is configured toreceive a first split light of the plurality of split lights. Thepolarization controller includes a first arm and a second arm. The firstarm includes a first phase shifter and a second phase shifter that areconfigured to be controlled to set a phase of the first arm relative tothe second arm. The grating coupler includes a first port to receivelight from the first arm and a second port configured to receive lightfrom the second arm. The dual-polarization grating coupler is configuredto couple the light from the first port into a first beam having a firstpolarization orientation. The dual-polarization grating coupler isconfigured to couple the light from the second arm into a second beamwith a second polarization orientation.

In an implementation, the LIDAR system further includes an optical mixerconfigured to receive second light of the plurality of split lights. Thedual-polarization grating coupler is configured to couple reflectedlight having the first polarization orientation into the first arm andconfigured to couple the reflected light having the second polarizationorientation into the second arm. The optical mixer may be configured tooutput an output signal in response to the reflected light and thesecond light.

In an implementation, the LIDAR system further includes a splitterconfigured to provide the first portion of the split light to thepolarization controller. The splitter is also configured to provide thesecond light to the optical mixer.

In an implementation, the LIDAR system further includes a first stageand a second stage. The first stage including a first 2×2 splitter andthe first phase shifter. The first 2×2 splitter connects to aninterconnect that feeds into the optical mixer. The second stageincluding a second 2×2 splitter and the second phase shifter.

In an implementation, the first port of the dual-polarization gratingcoupler is optically coupled to the second phase shifter.

In an implementation, the second beam with the second polarizationorientation is orthogonal to the first polarization orientation.

An implementation of the disclosure includes a system for an autonomousvehicle including an active polarization controlled coherent pixel arraycoupled to a LIDAR processing engine. Pixels in the active polarizationcontrolled coherent pixel array include a polarization controller and adual-polarization grating coupler. The polarization controller includesa first arm and a second arm. The first arm includes a first phaseshifter and a second phase shifter that can be controlled to set a phaseof the first arm relative to the second arm. The dual-polarizationgrating coupler includes a first port to receive light from the firstarm and a second port configured to receive light from the second arm.The dual-polarization grating coupler is configured to couple the lightfrom the first port into a first beam having a first polarizationorientation. The dual-polarization grating coupler is configured tocouple the light from the second arm into a second beam with a secondpolarization orientation.

In an implementation, the pixels in the active polarization controlledcoherent pixel array include an optical mixer configured to receivesecond light. The dual-polarization grating coupler is configured tocouple reflected light having the first polarization orientation intothe first arm and configured to couple the reflected light having thesecond polarization orientation into the second arm. The optical mixeris configured to output an output signal in response to the reflectedlight and the remaining portion of the split light.

In an implementation, the pixels in the active polarization controlledcoherent pixel array include a splitter configured to provide a firstportion of the split light to the polarization controller. The splitteris also configured to provide the remaining portion of the split lightto the optical mixer.

In an implementation, the first port of the dual-polarization gratingcoupler is optically coupled to the second phase shifter.

An implementation of the disclosure includes an autonomous vehiclesystem for an autonomous vehicle including a LIDAR pixel and one or moreprocessors. The LIDAR pixel includes a polarization controller, agrating coupler, and an optical mixer. The polarization controller isconfigured to receive a first portion of split light. The polarizationcontroller includes a first arm and a second arm. A phase shifter of thepolarization controller sets a phase of first-light propagating in thefirst arm relative to second-light propagating in the second arm. Thegrating coupler is configured to output an output beam in response toreceiving the first-light and the second-light. The grating coupler isconfigured to receive a reflected beam of the output beam. The opticalmixer is configured to output a beat signal in response to receiving aremaining portion of the split light and the reflected beam. The one ormore processors are configured to control the phase shifter in responseto receiving the beat signal from the pixel.

In an implementation, the grating coupler is a dual-polarization gratingcoupler configured to couple the first-light from the first arm into afirst beam having a first polarization orientation. Thedual-polarization grating coupler is configured to couple thesecond-light from the second arm into a second beam with a secondpolarization orientation orthogonal to the first polarizationorientation.

In an implementation, the one or more processors control the phaseshifter to increase a signal level of the beat signal.

In an implementation, the one or more processors control the phaseshifter to maximize a signal level of the beat signal.

In an implementation, the system for the autonomous vehicle includes acontrol system configured to control a powertrain of the autonomousvehicle in response to the beat signal.

In an implementation, the output beam is an infrared output beam.

In an implementation, the system for the autonomous vehicle includes asplitter configured to provide the first portion of the split light tothe polarization controller. The splitter is also configured to providethe remaining portion of the split light to the optical mixer.

In an implementation, the polarization controller includes a secondphase shifter.

In an implementation, the polarization controller includes a first stageand a second stage. The first stage includes a first 2×2 splitter andthe phase shifter. The first 2×2 splitter connects to an interconnectthat feeds into the optical mixer. The second stage includes a second2×2 splitter and the second phase shifter.

In an implementation, a first port of the grating coupler is opticallycoupled to the second phase shifter.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive implementations of the invention aredescribed with reference to the following figures, wherein likereference numerals refer to like parts throughout the various viewsunless otherwise specified.

FIG. 1A illustrates an example LIDAR device including a LIDAR pixelhaving active polarization control, in accordance with implementationsof the disclosure.

FIG. 1B illustrates an example LIDAR pixel including a first phaseshifter and a second phase shifter for active polarization control, inaccordance with implementations of the disclosure.

FIG. 2 demonstrates how more than one coherent pixel with activepolarization control can be combined into a focal plane array (FPA), inaccordance with implementations of the disclosure.

FIG. 3 demonstrates how an array of coherent pixels with activepolarization control can be used in an FMCW LIDAR system, in accordancewith implementations of the disclosure.

FIG. 4A illustrates an autonomous vehicle including an array of examplesensors, in accordance with implementations of the disclosure.

FIG. 4B illustrates a top view of an autonomous vehicle including anarray of example sensors, in accordance with implementations of thedisclosure.

FIG. 4C illustrates an example vehicle control system including sensors,a drivetrain, and a control system, in accordance with implementationsof the disclosure.

DETAILED DESCRIPTION

Implementations of active polarization control for LIDAR pixels aredescribed herein. In the following description, numerous specificdetails are set forth to provide a thorough understanding of theimplementations. One skilled in the relevant art will recognize,however, that the techniques described herein can be practiced withoutone or more of the specific details, or with other methods, components,or materials. In other instances, well-known structures, materials, oroperations are not shown or described in detail to avoid obscuringcertain aspects.

Reference throughout this specification to “one implementation” or “animplementation” means that a particular feature, structure, orcharacteristic described in connection with the implementation isincluded in at least one implementation of the present invention. Thus,the appearances of the phrases “in one implementation” or “in animplementation” in various places throughout this specification are notnecessarily all referring to the same implementation. Furthermore, theparticular features, structures, or characteristics may be combined inany suitable manner in one or more implementations.

Throughout this specification, several terms of art are used. Theseterms are to take on their ordinary meaning in the art from which theycome, unless specifically defined herein or the context of their usewould clearly suggest otherwise. For the purposes of this disclosure,the term “autonomous vehicle” includes vehicles with autonomous featuresat any level of autonomy of the SAE International standard J3016.

In aspects of this disclosure, visible light may be defined as having awavelength range of approximately 380 nm-700 nm. Non-visible light maybe defined as light having wavelengths that are outside the visiblelight range, such as ultraviolet light and infrared light. Infraredlight having a wavelength range of approximately 700 nm-1 mm includesnear-infrared light. In aspects of this disclosure, near-infrared lightmay be defined as having a wavelength range of approximately 700 nm-1.6μm.

In aspects of this disclosure, the term “transparent” may be defined ashaving greater than 90% transmission of light. In some aspects, the term“transparent” may be defined as a material having greater than 90%transmission of visible light.

Frequency Modulated Continuous Wave (FMCW) LIDAR directly measures rangeand velocity of an object by directing a frequency modulated, collimatedlight beam at the object. The light that is reflected from the object iscombined with a tapped version of the beam. The frequency of theresulting beat tone is proportional to the distance of the object fromthe LIDAR system once corrected for the doppler shift that requires asecond measurement. The two measurements, which may or may not beperformed at the same time, provide both range and velocity information.

FMCW LIDAR can take advantage of integrated photonics for improvedmanufacturability and performance. Integrated photonic systems typicallymanipulate single optical modes using micron-scale waveguiding devices.

Coherent light generated by FMCW LIDAR reflecting off of a diffusesurface produces a speckle pattern, which is characterized by a randomintensity and phase profile in the reflected optical field. This specklefield reduces the amount of power which can couple back into asingle-mode optical system. As an FMCW LIDAR beam is scanned across adiffuse surface, the reflected speckle field has time-varying behaviorwhich leads to a broadened signal spectrum.

Implementations of the disclosure include one or more coherent pixelswith active polarization control. Light in the coherent pixel may beevenly split into two “arms” and then the amplitude and relative phaseof the two arms of the pixel can be arbitrarily manipulated. The lightin the two arms may be passed into a dual-polarization optical coupler.This coupler may couple the light into free space with two orthogonalpolarizations.

By controlling the amplitude and phase of the two arms of the coherentpixel, the output polarization of light can be arbitrarily selected.Alternatively, by controlling the amplitude and phase of the two arms ofthe coherent pixel, it can be made arbitrarily sensitive to receiving aparticular polarization of light.

FIG. 1A illustrates an example LIDAR device 199 including a LIDAR pixel150 having active polarization control, in accordance withimplementations of the disclosure. LIDAR pixel 150 in FIG. 1A includes a1×2 splitter 152, an optical mixer 159, a grating coupler 161, and apolarization controller 180. Polarization controller 180 includes a 2×2splitter 156 and a phase shifter 157. Polarization controller 180includes a top arm 162 and a bottom arm 160.

Light 151 entering LIDAR pixel 150 can be split by a splitter (e.g. 1×2splitter 152). Light 151 may be infrared laser light generated by alaser (e.g. a continuous wave laser). In some implementations, the laserlight may be collimated. The split ratio of splitter 152 may be selectedas desired for the FMCW LIDAR system. A portion (e.g. between 70% and99%) of this split light propagates through an interconnect 153 to 2×2splitter 156. The remaining light (e.g. between 1% and 30%) leaving thebottom output port of 1×2 splitter 152 propagates through aninterconnect 154 to optical mixer 159. In some implementations, inputlight 151 and 1×2 splitter 152 may be replaced with two independentlight sources.

In the transmit direction, polarization controller 180 is configured toreceive a first portion of the split light that is split by 1×2 splitter152. The first portion of the split light propagates to polarizationcontroller 180 by way of interconnect 153. Light entering the 2×2splitter 156 is split between its two output ports. The top output portof 2×2 splitter 156 starts the “top arm” 162 of polarization controller180 and the bottom port of 2×2 splitter 156 starts the “bottom arm” 160of polarization controller 180. In some implementations, the split ratiobetween the top port and the bottom port of 2×2 splitter 156 is 50:50,however other split ratios may be selected if desired. Light in the toparm 162 passes through phase shifter 157 which can be controlled inorder to arbitrarily set the phase of the light in top arm 162 relativeto bottom arm 160.

Phase shifter 157 sets a phase of top-light propagating in top arm 162relative to bottom-light propagating in bottom arm 160. In FIG. 1A,processing logic 190 is configured to control phase shifter 157. Lightin top arm 162 propagates into a top port 168 of grating coupler 161while light in the bottom arm 160 propagates into a bottom port 169 ofgrating coupler 161. Grating coupler 161 may be a dual-polarizationgrating coupler configured to outcouple a first polarization orientationof light and a second polarization orientation of light that isorthogonal to the first polarization orientation of light. Gratingcoupler 161 couples light from top port 168 into a first polarizationbeam (e.g. “TE” polarized beam) and couples light from bottom port 169into a second polarization beam (e.g. “TM” polarized beam), in someimplementations. These two orthogonal beams superimpose to form anoutput beam of light 193 with arbitrary polarization which is determinedby the state of phase shifter 157. Thus, grating coupler 161 isconfigured to output an output beam of light 193 in response toreceiving top-light propagating in top arm 162 and bottom-lightpropagating in bottom arm 160.

In the illustrated implementation, grating coupler 161 is presented asthe “antenna.” However, an equivalent, alternative, or similar systemcan be implemented using polarization rotators, polarization combiners,or edge emitters.

In the receive direction, arbitrarily-polarized light 194 enters gratingcoupler 161. Light with the first polarization couples into top arm 162and passes through phase shifter 157. Light with the second polarizationcouples into bottom arm 160. The light in both arms then passes through2×2 splitter 156. Phase shifter 157 can be controlled such that amaximum amount of light couples into the bottom port of 2×2 splitter 156which connects to interconnect 163. The light in interconnect 163 is fedinto optical mixer 159, which combines it with the light in interconnect154. The light in interconnect 154 is the remaining light from the firstportion of light propagating in interconnect 153. Thus, optical mixer159 is configured to output an output signal 164 in response toreceiving the remaining portion of the split light and the reflectedbeam 194 (propagating through bottom arm 160 and 2×2 splitter 156).Optical mixer 159 converts these mixed optical signals (light ininterconnects 163 and interconnects 154) to the electrical domain,producing one or more output signals 164. For example, output signal 164may be an electronic signal such as a “beat signal.”

As described above, phase shifter 157 sets a phase of top-lightpropagating in top arm 162 relative to bottom-light propagating inbottom arm 160. In the illustrated implementation of FIG. 1A, processinglogic 190 is configured to control phase shifter 157 in response toreceiving beat signal 164 from LIDAR pixel 150. In some implementations,processing logic 190 is configured to drive phase shifter 157 todifferent phase values and then select the phase value that generatesthe beat signal 164 with the highest amplitude and drive that selectedphase value onto phase shifter 157 to increase or even maximize a signallevel of the beat signal 164. As different target surfaces reflectdifferent polarization orientations, processing logic 190 may drivephase shifter 157 to different phase values that increase an amplitudeof beat signal 164 due to the different polarizations of light reflectedby different target surfaces. In some implementations, processing logic190 receives beat signals 164 from a plurality of LIDAR pixels 150 andgenerates an image 191 from the plurality of beat signals.

FIG. 1B illustrates an example LIDAR pixel 149 including a first phaseshifter 107 and a second phase shifter 109 for active polarizationcontrol, in accordance with implementations of the disclosure. Light 101entering the coherent pixel 149 can be split by a splitter (e.g. 1×2splitter 102). The split ratio of this splitter may be selected asdesired for the FMCW LIDAR system. A portion of this split light (e.g.between 70% and 99%) propagates through an interconnect 103 to a 2×2splitter 105. The remaining light (e.g. between 1% and 30%) leaving thebottom output port of the 1×2 splitter propagates through aninterconnect 104 to an optical mixer 106. In some implementations, inputlight 101 and 1×2 splitter 102 may be replaced with two independentlight sources.

In the transmit direction, light entering the 2×2 splitter 105 is splitbetween its two output ports (which constitute the first stage of thepolarization controller 130 with a “top arm” and “bottom arm”). Thefirst stage includes first 2×2 splitter 105 and first phase shifter 107.In an implementation of coherent pixel 149, the split ratio is 50:50,however other split ratios may be selected if desired. Light in the toparm passes through a first phase shifter 107 which can be controlled inorder to arbitrarily set the phase of the light in the top arm relativeto the bottom arm.

The light in the top and bottom arms enter a second 2×2 splitter 108(the second stage of polarization controller 130). The second stageincludes second 2×2 splitter 108 and second phase shifter 109. Dependingon the phase shift of the two arms, the amplitude of light leaving thetop and bottom ports of splitter 108 can be controlled. Light in the toparm of this second stage passes through second phase shifter 109 whichcan be controlled to arbitrarily set the relative phase of the top andbottom arms of the second stage. Light in the top arm propagates intothe top port 118 of the dual-polarization grating coupler 111 whilelight in the bottom arm 110 propagates into the bottom port 119 of thedual-polarization grating coupler 111. Top port 118 is optically coupledto second phase shifter 109. The grating coupler 111 couples light fromthe top port 118 into a first polarized beam and couples light from thebottom port 119 into a second orthogonal polarized beam. These twoorthogonal beams superimpose to form a beam of light 143 with arbitrarypolarization which is determined by the state of the two phase shifters107 and 109.

In the illustrated implementation, dual-polarization grating coupler 111is presented as the “antenna.” However, an equivalent, alternative, orsimilar system can be implemented using polarization rotators,polarization combiners, or edge emitters.

In the receive direction, arbitrarily-polarized light 144 entersdual-polarization grating coupler 111. Light with the first polarizationcouples into the top arm 112 of the second stage and passes throughsecond phase shifter 109. Light with the second polarization couplesinto the bottom arm 110 of the second stage. The light in both arms thenpasses through the 2×2 splitter 108, entering the first stage. Light inthe top arm of the first stage passes through first phase shifter 107.Light in both arms of the first stage pass through the 2×2 splitter 105.First phase shifter 107 and second phase shifter 109 can be controlledsuch that a maximum amount of light couples into the bottom port of 2×2splitter 105 which connects to interconnect 113. The light in 113 is fedinto the optical mixer 106, which combines it with the light ininterconnect 104. Optical mixer 106 converts this mixed optical signalto the electrical domain, producing one or more output signals 114.

FIG. 2 demonstrates how more than one coherent pixel 203 with activepolarization control can be combined into a focal plane array (FPA) 201,in accordance with implementations of the disclosure. Coherent pixel 203may be implemented with the designs of LIDAR pixel 149 and/or LIDARpixel 150. Multiple optical channels 202 enter the array. These can bediscrete parallel channels or switched between the pixels using anoptical circuit. In some implementations, the same continuous wave (CW)infrared laser provides laser light for each of the optical channels202. Waveguides, optical fibers, micro-optical components, opticalamplifiers and/or photonic circuits may be implemented so that each ofchannels 202 receives a portion of the laser light from the CW infraredlaser. Light enters each coherent pixel (e.g. 203) which manipulates,transmits, and receives the light with arbitrary polarizations 204 aspreviously described. The received light is converted into an array ofoutput electrical signals 205. Image processing may be performed on thearray of output electrical signals 205 to generate an image of anenvironment imaged by FPA 201.

FIG. 3 demonstrates how the array of coherent pixels with activepolarization control can be used in an FMCW LIDAR system 399, inaccordance with implementations of the disclosure. In FIG. 3, a lens 300takes input from active polarization controlled coherent pixel array301. Active polarization controlled coherent pixel array 301 may includeFPA 201 in some implementations. Lens 300 also receives output beamswith a range of angles 306. The pixels in the active polarizationcontrolled coherent pixel array 301 are controlled by an FPA drivermodule 304. An individual pixel in the array may be turned on to emitand receive light or multiple simultaneous pixels in the array may beturned on to simultaneously emit or receive light. Light emitted by theactive polarization controlled coherent pixel array 301 is produced by alaser array with Q parallel channels 303. This laser array may beintegrated directly with the active polarization controlled coherentpixel array 301 or may be a separate module packaged alongside activepolarization controlled coherent pixel array 301. The laser array iscontrolled by a laser driver module 305, which receives control signalsfrom a LIDAR processing engine 302 via a digital to analog converter(DAC) 307. LIDAR processing engine 302 also controls FPA driver 304 andsends and receives data from active polarization controlled coherentpixel array 301.

LIDAR processing engine 302 includes a microcomputer 308. Microcomputer308 may process data coming from FPA system 330 and send control signalsto FPA system 330 via FPA driver 304 and laser controller 305. Signalsare received by N-channel receiver 309 of LIDAR processing engine 302.These incoming signals are digitized using a set of M-channel analog todigital converters (ADC) 310 and microcomputer 308 is configured toreceive the digitized version of the signals.

FIG. 4A illustrates an example autonomous vehicle 400 that may includethe LIDAR designs of FIGS. 1A-3, in accordance with aspects of thedisclosure. The illustrated autonomous vehicle 400 includes an array ofsensors configured to capture one or more objects of an externalenvironment of the autonomous vehicle and to generate sensor datarelated to the captured one or more objects for purposes of controllingthe operation of autonomous vehicle 400. FIG. 4A shows sensor 433A,433B, 433C, 433D, and 433E. FIG. 4B illustrates a top view of autonomousvehicle 400 including sensors 433F, 433G, 433H, and 433I in addition tosensors 433A, 433B, 433C, 433D, and 433E. Any of sensors 433A, 433B,433C, 433D, 433E, 433F, 433G, 433H, and/or 433I may include LIDARdevices that include the designs of FIGS. 1A-3. FIG. 4C illustrates ablock diagram of an example system 499 for autonomous vehicle 400. Forexample, autonomous vehicle 400 may include powertrain 402 includingprime mover 404 powered by energy source 406 and capable of providingpower to drivetrain 408. Autonomous vehicle 400 may further includecontrol system 410 that includes direction control 412, powertraincontrol 414, and brake control 416. Autonomous vehicle 400 may beimplemented as any number of different vehicles, including vehiclescapable of transporting people and/or cargo and capable of traveling ina variety of different environments. It will be appreciated that theaforementioned components 402-416 can vary widely based upon the type ofvehicle within which these components are utilized.

The implementations discussed hereinafter, for example, will focus on awheeled land vehicle such as a car, van, truck, or bus. In suchimplementations, prime mover 404 may include one or more electric motorsand/or an internal combustion engine (among others). The energy sourcemay include, for example, a fuel system (e.g., providing gasoline,diesel, hydrogen), a battery system, solar panels or other renewableenergy source, and/or a fuel cell system. Drivetrain 408 may includewheels and/or tires along with a transmission and/or any othermechanical drive components suitable for converting the output of primemover 404 into vehicular motion, as well as one or more brakesconfigured to controllably stop or slow the autonomous vehicle 400 anddirection or steering components suitable for controlling the trajectoryof the autonomous vehicle 400 (e.g., a rack and pinion steering linkageenabling one or more wheels of autonomous vehicle 400 to pivot about agenerally vertical axis to vary an angle of the rotational planes of thewheels relative to the longitudinal axis of the vehicle). In someimplementations, combinations of powertrains and energy sources may beused (e.g., in the case of electric/gas hybrid vehicles). In someimplementations, multiple electric motors (e.g., dedicated to individualwheels or axles) may be used as a prime mover.

Direction control 412 may include one or more actuators and/or sensorsfor controlling and receiving feedback from the direction or steeringcomponents to enable the autonomous vehicle 400 to follow a desiredtrajectory. Powertrain control 414 may be configured to control theoutput of powertrain 402, e.g., to control the output power of primemover 404, to control a gear of a transmission in drivetrain 408,thereby controlling a speed and/or direction of the autonomous vehicle400. Brake control 416 may be configured to control one or more brakesthat slow or stop autonomous vehicle 400, e.g., disk or drum brakescoupled to the wheels of the vehicle.

Other vehicle types, including but not limited to off-road vehicles,all-terrain or tracked vehicles, or construction equipment willnecessarily utilize different powertrains, drivetrains, energy sources,direction controls, powertrain controls and brake controls, as will beappreciated by those of ordinary skill having the benefit of the instantdisclosure. Moreover, in some implementations some of the components canbe combined, e.g., where directional control of a vehicle is primarilyhandled by varying an output of one or more prime movers. Therefore,implementations disclosed herein are not limited to the particularapplication of the herein-described techniques in an autonomous wheeledland vehicle.

In the illustrated implementation, autonomous control over autonomousvehicle 400 is implemented in vehicle control system 420, which mayinclude one or more processors in processing logic 422 and one or morememories 424, with processing logic 422 configured to execute programcode (e.g. instructions 426) stored in memory 424. Processing logic 422may include graphics processing unit(s) (GPUs) and/or central processingunit(s) (CPUs), for example. Vehicle control system 420 may beconfigured to control powertrain 402 of autonomous vehicle 400 inresponse to an output of the optical mixer of a LIDAR pixel such asLIDAR pixel 149 or 150. Vehicle control system 420 may be configured tocontrol powertrain 402 of autonomous vehicle 400 in response to outputsfrom a plurality of LIDAR pixels. Vehicle control system 420 may beconfigured to control powertrain 402 of autonomous vehicle 400 inresponse to outputs from microcomputer 308 generated based on signalsreceived from FPA system 330.

Sensors 433A—433I may include various sensors suitable for collectingdata from an autonomous vehicle's surrounding environment for use incontrolling the operation of the autonomous vehicle. For example,sensors 433A—433I can include RADAR unit 434, LIDAR unit 436, 3Dpositioning sensor(s) 438, e.g., a satellite navigation system such asGPS, GLONASS, BeiDou, Galileo, or Compass. The LIDAR designs of FIGS.1A-3 may be included in LIDAR unit 436. LIDAR unit 436 may include aplurality of LIDAR sensors that are distributed around autonomousvehicle 400, for example. In some implementations, 3D positioningsensor(s) 438 can determine the location of the vehicle on the Earthusing satellite signals. Sensors 433A—433I can optionally include one ormore ultrasonic sensors, one or more cameras 440, and/or an InertialMeasurement Unit (IMU) 442. In some implementations, camera 440 can be amonographic or stereographic camera and can record still and/or videoimages. Camera 440 may include a Complementary Metal-Oxide-Semiconductor(CMOS) image sensor configured to capture images of one or more objectsin an external environment of autonomous vehicle 400. IMU 442 caninclude multiple gyroscopes and accelerometers capable of detectinglinear and rotational motion of autonomous vehicle 400 in threedirections. One or more encoders (not illustrated) such as wheelencoders may be used to monitor the rotation of one or more wheels ofautonomous vehicle 400.

The outputs of sensors 433A—433I may be provided to control subsystems450, including, localization subsystem 452, trajectory subsystem 456,perception subsystem 454, and control system interface 458. Localizationsubsystem 452 is configured to determine the location and orientation(also sometimes referred to as the “pose”) of autonomous vehicle 400within its surrounding environment, and generally within a particulargeographic area. The location of an autonomous vehicle can be comparedwith the location of an additional vehicle in the same environment aspart of generating labeled autonomous vehicle data. Perception subsystem454 may be configured to detect, track, classify, and/or determineobjects within the environment surrounding autonomous vehicle 400.Trajectory subsystem 456 is configured to generate a trajectory forautonomous vehicle 400 over a particular timeframe given a desireddestination as well as the static and moving objects within theenvironment. A machine learning model in accordance with severalimplementations can be utilized in generating a vehicle trajectory.Control system interface 458 is configured to communicate with controlsystem 410 in order to implement the trajectory of the autonomousvehicle 400. In some implementations, a machine learning model can beutilized to control an autonomous vehicle to implement the plannedtrajectory.

It will be appreciated that the collection of components illustrated inFIG. 4C for vehicle control system 420 is merely exemplary in nature.Individual sensors may be omitted in some implementations. In someimplementations, different types of sensors illustrated in FIG. 4C maybe used for redundancy and/or for covering different regions in anenvironment surrounding an autonomous vehicle. In some implementations,different types and/or combinations of control subsystems may be used.Further, while subsystems 452-458 are illustrated as being separate fromprocessing logic 422 and memory 424, it will be appreciated that in someimplementations, some or all of the functionality of subsystems 452-458may be implemented with program code such as instructions 426 residentin memory 424 and executed by processing logic 422, and that thesesubsystems 452-458 may in some instances be implemented using the sameprocessor(s) and/or memory. Subsystems in some implementations may beimplemented at least in part using various dedicated circuit logic,various processors, various field programmable gate arrays (“FPGA”),various application-specific integrated circuits (“ASIC”), various realtime controllers, and the like, as noted above, multiple subsystems mayutilize circuitry, processors, sensors, and/or other components.Further, the various components in vehicle control system 420 may benetworked in various manners.

In some implementations, autonomous vehicle 400 may also include asecondary vehicle control system (not illustrated), which may be used asa redundant or backup control system for autonomous vehicle 400. In someimplementations, the secondary vehicle control system may be capable ofoperating autonomous vehicle 400 in response to a particular event. Thesecondary vehicle control system may only have limited functionality inresponse to the particular event detected in primary vehicle controlsystem 420. In still other implementations, the secondary vehiclecontrol system may be omitted.

In some implementations, different architectures, including variouscombinations of software, hardware, circuit logic, sensors, and networksmay be used to implement the various components illustrated in FIG. 4C.Each processor may be implemented, for example, as a microprocessor andeach memory may represent the random access memory (“RAM”) devicescomprising a main storage, as well as any supplemental levels of memory,e.g., cache memories, non-volatile or backup memories (e.g.,programmable or flash memories), or read-only memories. In addition,each memory may be considered to include memory storage physicallylocated elsewhere in autonomous vehicle 400, e.g., any cache memory in aprocessor, as well as any storage capacity used as a virtual memory,e.g., as stored on a mass storage device or another computer controller.Processing logic 422 illustrated in FIG. 4C, or entirely separateprocessing logic, may be used to implement additional functionality inautonomous vehicle 400 outside of the purposes of autonomous control,e.g., to control entertainment systems, to operate doors, lights, orconvenience features.

In addition, for additional storage, autonomous vehicle 400 may alsoinclude one or more mass storage devices, e.g., a removable disk drive,a hard disk drive, a direct access storage device (“DASD”), an opticaldrive (e.g., a CD drive, a DVD drive), a solid state storage drive(“SSD”), network attached storage, a storage area network, and/or a tapedrive, among others. Furthermore, autonomous vehicle 400 may include auser interface 464 to enable autonomous vehicle 400 to receive a numberof inputs from a passenger and generate outputs for the passenger, e.g.,one or more displays, touchscreens, voice and/or gesture interfaces,buttons and other tactile controls. In some implementations, input fromthe passenger may be received through another computer or electronicdevice, e.g., through an app on a mobile device or through a webinterface.

In some implementations, autonomous vehicle 400 may include one or morenetwork interfaces, e.g., network interface 462, suitable forcommunicating with one or more networks 470 (e.g., a Local Area Network(“LAN”), a wide area network (“WAN”), a wireless network, and/or theInternet, among others) to permit the communication of information withother computers and electronic devices, including, for example, acentral service, such as a cloud service, from which autonomous vehicle400 receives environmental and other data for use in autonomous controlthereof. In some implementations, data collected by one or more sensors433A—433I can be uploaded to computing system 472 through network 470for additional processing. In such implementations, a time stamp can beassociated with each instance of vehicle data prior to uploading.

Processing logic 422 illustrated in FIG. 4C, as well as variousadditional controllers and subsystems disclosed herein, generallyoperates under the control of an operating system and executes orotherwise relies upon various computer software applications,components, programs, objects, modules, or data structures, as may bedescribed in greater detail below. Moreover, various applications,components, programs, objects, or modules may also execute on one ormore processors in another computer coupled to autonomous vehicle 400through network 470, e.g., in a distributed, cloud-based, orclient-server computing environment, whereby the processing required toimplement the functions of a computer program may be allocated tomultiple computers and/or services over a network.

Routines executed to implement the various implementations describedherein, whether implemented as part of an operating system or a specificapplication, component, program, object, module or sequence ofinstructions, or even a subset thereof, will be referred to herein as“program code.” Program code typically comprises one or moreinstructions that are resident at various times in various memory andstorage devices, and that, when read and executed by one or moreprocessors, perform the steps necessary to execute steps or elementsembodying the various aspects of the invention. Moreover, whileimplementations have and hereinafter may be described in the context offully functioning computers and systems, it will be appreciated that thevarious implementations described herein are capable of beingdistributed as a program product in a variety of forms, and thatimplementations can be implemented regardless of the particular type ofcomputer readable media used to actually carry out the distribution.Examples of computer readable media include tangible, non-transitorymedia such as volatile and non-volatile memory devices, floppy and otherremovable disks, solid state drives, hard disk drives, magnetic tape,and optical disks (e.g., CD-ROMs, DVDs) among others.

In addition, various program code described hereinafter may beidentified based upon the application within which it is implemented ina specific implementation. However, it should be appreciated that anyparticular program nomenclature that follows is used merely forconvenience, and thus the invention should not be limited to use solelyin any specific application identified and/or implied by suchnomenclature. Furthermore, given the typically endless number of mannersin which computer programs may be organized into routines, procedures,methods, modules, objects, and the like, as well as the various mannersin which program functionality may be allocated among various softwarelayers that are resident within a typical computer (e.g., operatingsystems, libraries, API's, applications, applets), it should beappreciated that the invention is not limited to the specificorganization and allocation of program functionality described herein.

Those skilled in the art, having the benefit of the present disclosure,will recognize that the exemplary environment illustrated in FIG. 4C isnot intended to limit implementations disclosed herein. Indeed, thoseskilled in the art will recognize that other alternative hardware and/orsoftware environments may be used without departing from the scope ofimplementations disclosed herein.

The term “processing logic” (e.g. processing logic 190 or 422) in thisdisclosure may include one or more processors, microprocessors,multi-core processors, Application-specific integrated circuits (ASIC),and/or Field Programmable Gate Arrays (FPGAs) to execute operationsdisclosed herein. In some implementations, memories (not illustrated)are integrated into the processing logic to store instructions toexecute operations and/or store data. Processing logic may also includeanalog or digital circuitry to perform the operations in accordance withimplementations of the disclosure.

A “memory” or “memories” described in this disclosure may include one ormore volatile or non-volatile memory architectures. The “memory” or“memories” may be removable and non-removable media implemented in anymethod or technology for storage of information such ascomputer-readable instructions, data structures, program modules, orother data. Example memory technologies may include RAM, ROM, EEPROM,flash memory, CD-ROM, digital versatile disks (DVD), high-definitionmultimedia/data storage disks, or other optical storage, magneticcassettes, magnetic tape, magnetic disk storage or other magneticstorage devices, or any other non-transmission medium that can be usedto store information for access by a computing device.

A Network may include any network or network system such as, but notlimited to, the following: a peer-to-peer network; a Local Area Network(LAN); a Wide Area Network (WAN); a public network, such as theInternet; a private network; a cellular network; a wireless network; awired network; a wireless and wired combination network; and a satellitenetwork.

Communication channels may include or be routed through one or morewired or wireless communication utilizing IEEE 802.11 protocols, SPI(Serial Peripheral Interface), I²C (Inter-Integrated Circuit), USB(Universal Serial Port), CAN (Controller Area Network), cellular dataprotocols (e.g. 3G, 4G, LTE, 5G), optical communication networks,Internet Service Providers (ISPs), a peer-to-peer network, a Local AreaNetwork (LAN), a Wide Area Network (WAN), a public network (e.g. “theInternet”), a private network, a satellite network, or otherwise.

A computing device may include a desktop computer, a laptop computer, atablet, a phablet, a smartphone, a feature phone, a server computer, orotherwise. A server computer may be located remotely in a data center orbe stored locally.

The processes explained above are described in terms of computersoftware and hardware. The techniques described may constitutemachine-executable instructions embodied within a tangible ornon-transitory machine (e.g., computer) readable storage medium, thatwhen executed by a machine will cause the machine to perform theoperations described. Additionally, the processes may be embodied withinhardware, such as an application specific integrated circuit (“ASIC”) orotherwise.

A tangible non-transitory machine-readable storage medium includes anymechanism that provides (i.e., stores) information in a form accessibleby a machine (e.g., a computer, network device, personal digitalassistant, manufacturing tool, any device with a set of one or moreprocessors, etc.). For example, a machine-readable storage mediumincludes recordable/non-recordable media (e.g., read only memory (ROM),random access memory (RAM), magnetic disk storage media, optical storagemedia, flash memory devices, etc.).

The above description of illustrated implementations of the invention,including what is described in the Abstract, is not intended to beexhaustive or to limit the invention to the precise forms disclosed.While specific implementations of, and examples for, the invention aredescribed herein for illustrative purposes, various modifications arepossible within the scope of the invention, as those skilled in therelevant art will recognize.

These modifications can be made to the invention in light of the abovedetailed description. The terms used in the following claims should notbe construed to limit the invention to the specific implementationsdisclosed in the specification. Rather, the scope of the invention is tobe determined entirely by the following claims, which are to beconstrued in accordance with established doctrines of claiminterpretation.

What is claimed is:
 1. A light detection and ranging (LIDAR) systemcomprising: a laser that is configured to generate light; a splitterthat is configured to split the light into a plurality of split lights;a polarization controller configured to receive a first split light ofthe plurality of split lights, the polarization controller including afirst arm and a second arm, wherein the first arm includes a first phaseshifter and a second phase shifter that are configured to be controlledto set a phase of light that passes through the first arm relative tothe second arm, wherein the polarization controller includes at leastone 2×2 splitter coupled to the first arm and the second arm; and adual-polarization grating coupler including a first port to receivelight from the first arm and a second port configured to receive lightfrom the second arm, wherein the dual-polarization grating coupler isconfigured to couple the light from the first port into a first beamhaving a first polarization orientation, and wherein thedual-polarization grating coupler is configured to couple the light fromthe second arm into a second beam with a second polarizationorientation, wherein the first port of the dual polarization gratingcoupler is optically coupled directly to the second phase shifter. 2.The LIDAR system of claim 1 further comprising: an optical mixerconfigured to receive a second light of the plurality of split lights,wherein the dual-polarization grating coupler is configured to couplereflected light having the first polarization orientation into the firstarm and configured to couple the reflected light having the secondpolarization orientation into the second arm, and wherein the opticalmixer is configured to output an output signal in response to thereflected light and the second light, wherein the reflected light is atleast one of the first beam or the second beam reflected from at leastone object in a LIDAR operating environment.
 3. The LIDAR system ofclaim 2, wherein the splitter is coupled to the polarization controllerand is coupled to the optical mixer to provide the second light to theoptical mixer.
 4. The LIDAR system of claim 2, wherein the at least one2×2 splitter includes a first 2×2 splitter and a second 2×2 splitter,wherein the polarization controller includes: a first stage includingthe first 2×2 splitter and the first phase shifter, wherein the first2×2 splitter connects to an interconnect that feeds into the opticalmixer; and a second stage including -the second 2×2 splitter and thesecond phase shifter.
 5. The LIDAR system of claim 2, wherein apolarization of the reflected light is at least partially based on oneor more surfaces of the at least one object.
 6. The LIDAR system ofclaim 1, wherein the second beam with the second polarizationorientation is orthogonal to the first polarization orientation.
 7. TheLIDAR system of claim 1, wherein the first beam and the second beamsuperimpose to form a combined beam having an arbitrary polarization. 8.The LIDAR system of claim 7, wherein the arbitrary polarization is atleast partially determined by the first phase shifter and the secondphase shifter.
 9. An autonomous vehicle control system for an autonomousvehicle, the system comprising: a light detection and ranging (LIDAR)processing engine; and an active polarization controlled coherent pixelarray coupled to the LIDAR processing engine, wherein pixels in theactive polarization controlled coherent pixel array include: apolarization controller including a first arm and a second arm, whereinthe first arm includes a first phase shifter and a second phase shifterthat can be controlled to set a phase of the first arm relative to thesecond arm, wherein the polarization controller includes at least one2×2 splitter coupled to the first arm and the second arm; and adual-polarization grating coupler including a first port to receivelight from the first arm and a second port configured to receive lightfrom the second arm, wherein the dual-polarization grating coupler isconfigured to couple the light from the first port into a first beamhaving a first polarization orientation, and wherein the dualpolarization grating coupler is configured to couple the light from thesecond arm into a second beam with a second polarization orientation,wherein the first port of the dual-polarization grating coupler isoptically coupled directly to the second phase shifter.
 10. The systemof claim 9, wherein the pixels in the active polarization controlledcoherent pixel array includes: an optical mixer configured to receive aportion of split light, wherein the dual-polarization grating coupler isconfigured to couple reflected light having the first polarizationorientation into the first arm and configured to couple the reflectedlight having the second polarization orientation into the second arm,and wherein the optical mixer is configured to output an output signalin response to the reflected light and the portion of split light,wherein the reflected light is at least one of the first beam or thesecond beam reflected from at least one object in a LIDAR operatingenvironment.
 11. The system of claim 10, wherein the pixels in theactive polarization controlled coherent pixel array includes: a splittercoupled to the polarization controller and coupled to the optical mixerto provide first light to the polarization controller, the splitter alsobeing configured to provide the second light to the optical mixer,wherein the second light is the portion of split light.
 12. The LIDARsystem of claim 9, wherein the first beam and the second beamsuperimpose to form a combined beam having an arbitrary polarizationthat is at least partially determined by the first phase shifter and thesecond phase shifter.
 13. A system for an autonomous vehicle, the systemcomprising: a light detection and ranging (LIDAR) pixel including: apolarization controller configured to receive a first portion of splitlight, wherein the polarization controller includes a first arm and asecond arm, and wherein a phase shifter of the polarization controllersets a phase of first-light propagating in the first arm relative tosecond-light propagating in the second arm, wherein the polarizationcontroller includes at least one 2×2 splitter coupled to the first armand the second arm; a grating coupler configured to output an outputbeam in response to receiving the first-light and the second-light,wherein the grating coupler is configured to receive a reflected beamthat is a reflection of the output beam off of an object in a LIDARoperating environment, wherein a first port of the grating coupler isoptically coupled directly to the phase shifter; and an optical mixerconfigured to output a beat signal in response to receiving a remainingportion of the split light and the reflected beam; one or moreprocessors configured to control the phase shifter in response toreceiving the beat signal from the pixel; and a control systemconfigured to control the autonomous vehicle in response to the beatsignal.
 14. The system of claim 13, wherein the grating coupler is adual-polarization grating coupler configured to couple the first-lightfrom the first arm into a first beam having a first polarizationorientation, and wherein the dual-polarization grating coupler isconfigured to couple the second-light from the second arm into a secondbeam with a second polarization orientation orthogonal to the firstpolarization orientation.
 15. The system of claim 13, wherein the one ormore processors control the phase shifter to increase a signal level ofthe beat signal.
 16. The system of claim 13, wherein the one or moreprocessors control the phase shifter to maximize a signal level of thebeat signal.
 17. The system of claim 13, wherein the output beam is aninfrared output beam.
 18. The system of claim 13 further comprising: asplitter coupled to the polarization controller and to the opticalmixer, wherein the splitter is configured to provide the first portionof the split light to the polarization controller, the splitter alsobeing configured to provide the remaining portion of the split light tothe optical mixer.
 19. The system of claim 13, wherein the polarizationcontroller includes a second phase shifter.
 20. The system of claim 19,wherein the at least one 2×2 splitter includes a first 2×2 splitter anda second 2×2 splitter, wherein the polarization controller includes: afirst stage including the first 2×2 splitter and the phase shifter,wherein the first 2×2 splitter connects to an interconnect that feedsinto the optical mixer; and a second stage including the second 2×2splitter and the second phase shifter.